The present invention relates to an improved flashback chamber structure for catheters. The flashback chamber of the present invention is constructed so as to permit the user to visually observe the relative rate of blood flow, to know if the flow is continuous, which in turn, indicates whether or not the needle tip is in a proper position in a vein or artery for subsequent advancement of the catheter coaxially with respect to a needle, which it slidably jackets, into the vein in which the needle tip has been properly positioned.
The flashback chamber structure, generally is composed of a main body portion which defines a blood receiving internal chamber subdivided into a maze or network or passageways of relatively small cross section. Preferably a slidable lid is in sealing engagement with the main body portion of the flashback chamber structure, in the preferred embodiment illustrated. To the lid or slide member, a hollow tube or plastic catheter is afixed so that it may be slidably advanced, or manipulated, relative to a needle, which it jackets by manipulating the slidable member.
More particularly a hollow needle is fixed relative to and extending outwardly of the forward end of the main body portion of the flashback chamber structure. The main body portion and slidable member are preferably provided with external gripping means which may be in the form of a pattern in relief, such as flutes. This accommodates coaxial movement of the lid or member relative to the main body portion as guided by guide means described hereinafter so that, after the needle point has been inserted correctly in a person's vein or artery, the catheter may be advanced without actually touching it during the advancement process and, hence, without the attendant danger of contaminating the same.
Within the main body portion, septums in a preferred embodiment are provided to define a relatively long blood path of relatively small cross sectional area, hereinafter referred to as chamber maze. In the preferred embodiment, an open mouth of the chamber structure is securely covered by a lid at all times during the needle and catheter insertion. The lid or slide member in a preferred embodiment is of suitable transparent plastic material to permit easy visual observation of the rate of blood flow into the passageways of the maze, that is, the blood path which is relatively long and of relatively small cross sectional area; thus, the visual progress of the blood flow ie, whether it is continuous or not, can be observed, which is an indication as to proper location of needle tip in a vein or artery prior to final advancement of the catheter.